1. Technical Field
The present invention relates generally to methods and apparatus for orthodontic treatment. In another aspect, the present invention relates to methods of making and using the archwire bracket force delivery system, more commonly referred to as orthodontic braces or orthodontic appliances. In particular, the present invention relates to the conversion of the known labial art to lingual applications as well as original concepts designed to meet the unique demands of the lingual environment.
2. Description of the Related Labial Art
Generally, orthodontic treatment of the teeth is accomplished by applying force to the teeth with a series of archwires positioned in and across a number of brackets. Since the beginning of orthodontics, in the late 1800's, orthodontists have been pursuing the goals of increased appliance resiliency, control, comfort to the patient, and easier manipulation for the doctor.
Edward H. Angle is considered the father of modern orthodontics. Angle's U.S. Pat. No. 678,453 discloses a rigid outer archwire with teeth tied to the archwire to draw them into position. The bands on the teeth were attachments that were really simple cleats. In 1925, in U.S. Pat. No. 1,584,501, Angle added a rectangular slot to the bracket with wings to receive tiewires. Because the slot was perpendicular to the long axis of the tooth it was called the Edgewise Appliance. The initial heavy gold archwire was bent to the shape of the malocclusion and was gradually straightened out. The device produced very precise control but was extremely rigid and non-resilient. To provide increased resiliency the sequential use of a number of single archwires, beginning with relatively small diameter round wires, and finishing with large rectangular wires, was incorporated in the Edgewise technique. Angle's Edgewise bracket has evolved into the Edgewise technique that is in common use today.
Typically, the archwire was secured in the archwire slot using wire ligatures twisted around the wings extending laterally on opposite sides of the slot. The use of elastomer O-rings in place of the wire ligatures was described by Anderson and Klein in U.S. Pat. No. 4,382,782. The use of elastomers was a definite step forward in the Edgewise technique. By their very nature, the elastomers provided a gentler and longer acting force. They were softer and were easier to install. However, the elastomer O-rings did have one problem; they absorbed water and lost some of their elastic force over time, necessitating replacement of the O rings.
Also, in 1925, Angle was issued U.S. Pat. No. 1,552,413, which disclosed a bracket designed to receive a rectangular archwire that was called a ribbon arch because the long axis of the archwire cross section was in the same plane as the long axis of the tooth. This bracket was locked with a pin which was held in place by bending the pin after it was inserted in the locking position. This bracket was later used by Spencer Atkinson and was developed into what was known as the Universal Technique. Atkinson's art was taught in U.S. Pat. Nos. 1,821,171; 2,196,516; and 2,305,916. Wildman, in U.S. Pat. No. 3,854,207, offered a self-ligating version of the Universal Technique in 1974.
J. W. Ford, in 1933 in U.S. Pat. No. 2,011,575, described a sleeve and tube unit that was probably the first self-ligating lingual bracket. The locking device was a friction lock.
McCoy presented a different approach that still used the gold arch technology. McCoy's bracket was simply a gold tube opened up to allow a snap fit to securely hold an appropriate round arch. A wide variety of torquing spurs were soldered to the arch. The gold arch allowed a full range of movement. These early efforts produced some very nice cases, even by modern standards, but the process was very demanding and time consuming. McCoy described the details of this process in U.S. Pat. No. 2,023,849. This patent was in the same year as the Ford patent. Because McCoy lectured showing treated cases, some people call McCoy the originator of self-ligating brackets.
The ribbon arch bracket was modified by Dr. P. R. Begg and was used extensively in what was known as the Begg technique. The Begg technique was well-received because it produced gentle forces which made it easy to start a case. It fell out of favor though because it was difficult to adequately finish cases. Begg's modification is described in U.S. Pat. No. 3,123,553 and used the pin groove of the Angle ribbon arch to attach a wide variety of torquing and rotational auxiliaries. In some iterations, Begg used a secondary archwire to provide torque control. Coordinating all these complex torque vectors made finishing cases difficult and led to the demise of the Begg technique.
To further increase the resiliency of the archwires, orthodontists began incorporating all sorts of geometric bends in almost every conceivable shape. An extreme example of this approach is described by Brader in U.S. Pat. No. 3,593,421. The downside of this was the difficulty of putting precise bends in the archwire. These archwires became too flimsy to control, and were eventually abandoned.
To provide increased resiliency and still maintain control, orthodontists sometimes turned to multiple archwires. J. D. Berke, in U.S. Pat. Nos. 2,406,527 and 2,705,367, described a bracket which is essentially a button with two channels separated by the body of the bracket. The two archwires were connected by rigid connectors between two teeth. In one configuration connectors were fixed and in another configuration they were slidable. This was the first mention of slidable, rigid interarch connectors. The archwire was connected to the tooth by pulling the two archwires away from each other and snapping the two archwires over the tooth. The archwires, returning to shape, moved the tooth into the proper position by seating the archwires in the archwire slot. The rigid sliding connectors helped in manipulation of the archwires but the rigid construction made this system difficult to use. Thus, this bracket was never produced in any significant quantities commercially.
Another approach was described by Joseph Johnson in U.S. Pat. Nos. 1,952,320; 2,665,480; and 2,759,265. Johnson incorporated two small diameter archwires held together in a ribbon arch configuration with the long axis going through the two wires parallel to the long axis of the tooth. This twin wire did produce increased resiliency but placing any compensating bends was impossible. This was a friction lock.
In 1952 Russell described in U.S. Pat. No. 2,671,964, a two piece unit that closed off the slot locking in twin wires as proposed by Johnson.
In 1965, S. M. Bien, in U.S. Pat. No. 3,193,930, proposed an interesting approach using one, two or three separated archwires. The channels that accepted the archwires were in the shape of V's and did not provide an edgewise slot.
U.S. Pat. No. 3,302,288 to Teppler discloses a similar two wire bracket arrangement using parallel spaced crossbars interconnected by a rigid member. Since this interarch connector was rigid it made this arrangement difficult to use. The archwires cannot be pulled apart easily to allow insertion and release.
Another attempt at attaining precision with two wires was described by Northcott in U.S. Pat. No. 3,775,850. Northcott connected two and three archwires together with interarch connectors. These connectors were rigid cast or brazed metal, both fixed and slidable. This rigid system was tied into the corresponding slots in the labial bracket. The sliding rigid connectors had to be tied in with twisted steel ligatures, however.
The problem with all of the two-wire techniques is the difficulty in putting in compensating bends. In theory, if the bracket of the tooth is put on the tooth in such a position that the channel of the bracket is in an ideal position, a straight archwire placed in this channel would produce a tooth positioned in the ideal position. In actual practice this does not happen, though. To compensate for the fact that this is not an ideal position the orthodontist had to make compensating bends in the archwire. Compensating bends in even a single archwire are difficult and time consuming for the orthodontist.
This problem was addressed by Dr. Larry Andrews using methods described in U.S. Pat. Nos. 3,477,128 and 3,660,900. Andrews attempted to position the slots in the bracket in such a relation to the base of the bracket that was applied to the tooth so that the slot assumed an ideal position in the average tooth. Since the brackets were generally put on the tooth by the orthodontist in the mouth using the orthodontist's trained eye, errors in position were inevitable. Also, not all teeth are average, and this also increases errors. So, the orthodontist must still finish cases with compensating bends. This is much easier with Andrews' straight arch system. Putting compensating bends in two wires is, from a practical point of view, impossible.
3. Description of the Related Lingual Art
Dr. A. J. Wildman's U.S. Pat. No. 3,842,503 in 1974 was the beginning of what is called lingual orthodontics. Wildman stated in this patent—“The archwires may be mounted on the lingual side of the teeth as well as the labial side, as previously done. This is possible because brackets may be secured directly to the teeth without bands. Thus, for cosmetic reasons or otherwise, it may be desired to mount a lingual archwire”. He also introduced the concept of cutting teeth off of a model of the teeth and placing them in an ideal position. The brackets could then be placed on the models and the resulting set-up could act as a means of making an ideal archwire. The brackets could then be transferred to the mouth in the ideal position by a variety of means, and the archwire could then be tied into the brackets on the teeth. This would produce an ideal position for the teeth. This technique was later refined and called the Class System.
This patent ('503) suggested using cast gold bases as a means of indexing. The brackets were brazed to the bases in a perfect position. The castings and brackets were then transferred to the teeth and cemented or bonded in place just as a gold inlay would be seated.
Wildman has previously developed lingual orthodontic methods and brackets as described in U.S. Pat. Nos. 3,748,740, which was a self-ligating Begg bracket; 3,780,437, which was the production version of the Edgelok bracket; 3,842,503, which described for the first time the concept of “lingual orthodontics” and the concept of the Class System; 3,854,207, which was a self ligating version of the Universal System; 4,443,187; 4,484,931, which was a method of bonding using burnished index tabs; and U.S. Pat. No. 4,443,189, which was a lingual bracket which locked in a second or auxiliary archwire. This lingual bracket was called “The Kelly Bracket” after the first patient it was tried upon. These concepts were a good start but needed further development.
In U.S. Pat. Nos. 4,337,037, 4,386,908, and 4,669,981 (1982, 1983 and 1987 respectively), Kurz described a series of shapes that he felt fit best on the lingual anatomical surfaces of the teeth. These shapes were incorporated in brackets that had to be tied either with steel ligatures or with elastomer O's. The steel wires were very sharp and uncomfortable to the patient. When plastic O's were used it was often necessary to use a double tie arrangement, with O rings doubled back on themselves in order to apply enough force from the O ring to properly seat the archwire. Orthodontists complained that this method was difficult and inefficient.
U.S. Pat. No. 6,485,299 to Wildman describes an insert configured to convert a non-self-ligating lingual bracket into a self-ligating bracket. The insert is removably attachable to the non-self-ligating lingual bracket and includes a self-ligating mechanism. According to a preferred embodiment, the bracket insert includes a pin, a tube, and a lock arm. The pin is configured to be removably secured to the non-self-ligating bracket. The tube is attached to or formed from an occlusal end of the retention pin. The lockarm is partially mounted within the tube and is capable of rotation between a ligating and non-ligating position. In its ligating position the lockarm securely retains an archwire within the archwire slot of the non-self-ligating bracket using detents in the rotating lockarm that snap into corresponding architecture in the body. This approach works very well but it does not lock an occlusal auxiliary archwire. An interarch connector between the two wires opens up all sorts of opportunities.
Thus, there is a need for an improvement in the arrangement described in the above patent. Ideally, the body would have an auxiliary slot that would allow insertion from the incisal direction. There would also be a typical edgewise slot that would allow insertion from the lingual direction. In U.S. Pat. No. 5,791,897, FIGS. 33-40B and the accompanying description explain the virtues of the occlusal auxiliary archwire and the edgewise archwire used together as a working arch. Another improvement would be the ability to use an edgewise archwire alone to add any necessary compensating bends.
The orthodontic profession needs a lingual self-ligating bracket that could lock in a single, light occlusal archwire to begin the unraveling of teeth in the first phase of treatment. In this system, an edgewise archwire would complement the occlusal archwire to provide ideal control of roots in all planes of space. A third, gingival archwire could be used to provide additional control. Further, a single archwire could be used in the edgewise slot to provide the fine finishing details. Many combinations expressing the needs of various techniques could be met with this arrangement. Accordingly, a need remains for a multiple archwire bracket that overcomes the deficiencies in the prior art.